A high-performance UV/visible photodetector of Cu2O/ZnO hybrid nanofilms on SWNT-based flexible conducting substrates

Abstract

In this report, we present a photosensing unit based on single-walled nanotubes (SWNTs) integrated with Cu₂O/ZnO hybrid nanofilms. 50 nm Cu₂O and 50 nm ZnO nanofilms are respectively deposited on a SWNT-coated polyethylene terephthalate (PET) sheet via a two-step sputtering process. The Cu₂O/ZnO nanofilm photodetector exhibits a rapid response (<100 ms), excellent responsive repeatability, robust stability and broadband photodetection range from 365 to 625 nm without external bias. Furthermore, the ZnO/Cu₂O nanofilm photodetector has also been fabricated by changing the deposition sequence of ZnO and Cu₂O. The photocurrent of the ZnO/Cu₂O nanofilm photodetector is one-fourth of that of the Cu₂O/ZnO nanofilm photodetector. We speculate that it might be attributed to the presence of the whispering-gallery mode (WGM) resonances in Cu₂O/ZnO hybrid nanofilms owing to the higher refractive index of Cu₂O, resulting in the enhancement of the light trapping and absorption. The high performance of the Cu₂O/ZnO nanofilm photodetector indicates that the Cu₂O/ZnO hybrid nanofilms on SWNT-based conducting substrates are suitable for mass production and application as high-sensitivity, fast response speed and flexible UV/visible photodetectors.